1. Field of the Invention
The invention relates to a packing seal which is intended in particular for reciprocating piston engines and which is preferably placed into a circumferential groove of a piston of such a reciprocating piston engine.
2. Description of Related Art
With reference to FIG. 2 of the attached drawings, a seal in the form of a packing seal is shown which is known from WO 95/14184. The packing seal marked 10 overall comprises at least two axially adjacent segment rings 1, which each have several sealing segments 3 and also many locking segments 4. The sealing segments 3 and the locking segments 4 taper in this case in a wedge-shape in opposite directions radially inward and outward, respectively, in both segment rings 1. These segments are provided inside each segment ring 1 in alternating order. The sealing elements 3 of the at least two segment rings overlap alternately and, by means of at least one spring element 2, such as a bearing spring washer, they are prestressed radially outward against a cylindrical wall--not shown--of a reciprocating piston engine, for example. Provided between the at least two segment rings 1 is a torsion protection formed by a bore 8 and an adjusting pin 9. The bores 8 penetrate two overlapping sealing segments 3 of the two axially adjacent segment rings 1. The torsion protection formed in connection with the two bores 8 and the adjusting pin 9 ensures that the provided reciprocal overlapping of the sealing segments 3 is maintained. So with this known packing seal, there must be a spring element 2, such as a bearing spring washer, which is responsible for the flawless functioning of the seal designed as packing seal. This spring element must exert a predetermined elastic force, directed in predetermined manner, throughout the useful life of the seal, although the spring element is exposed to high and also changing temperatures. Furthermore, the elastic force must be great enough that even under the action of high ignition and/or combustion pressures, the locking parts of the segment ring directly under pressure will not be pressed out of the overall arrangement. Thus, it has been shown that such a spring element must be designed relatively thick, in such a way that considerable groove depths are needed to receive the entire packing seal. Such considerable groove depths may lead to vibration problems that become noticeable as fluttering. This occurs in particular with high-speed, powerful engines, e.g. racing engines, and is attributable to resonance effects. In particular, with the aforementioned known seal it has been shown that the spring element necessary for operation entails not only an expense with respect to production, but in particular extensive changes are also necessary with a view to receiving the packing seal, and such a spring element impairs the functioning of the seal to the effect that when the readjusting rate of the spring element is reduced, changing energy generation and impact make possible--if only in the short-term--an undesired, increased passage of gas, which is also designated as "blow-by". Of course, a loss of power is inevitably connected with this.
On the other hand, the invention aims to provide a packing seal of the generic kind--overcoming the aforementioned difficulties--which ensures, with a simplified assembly and reliability of use, an arrangement of the sealing segments of the packing seal.